This invention relates to atomizing pump dispensers in general and more particularly to an improved single puff prepressure pump.
Various types of atomizing pump dispensers have been developed. The majority of these pump dispensers include a pump body in which there is formed a pump chamber, a piston disposed for reciprocal movement within the pump chamber a dispensing stem operatively coupled to the piston and adapted to receive an atomizer head, and valve means for selectively bringing the pump chamber in and out of communication with the container on which the pump is mounted. Typically, a check valve such as a ball check valve is utilized. During the dispensing stroke the pressure developed within the pump chamber closes the check valve so that material is forced out through the stem and atomizer. After dispensing, as the piston is returned to its normal position by biasing means such as a spring, the check valve opens to permit the pump chamber to refill.
However, pumps have also been developed which do not utilize such a check valve. Typical of this type of pump is that disclosed and claimed in U.S. Pat. No. 4,113,145, the disclosure of which is hereby incorporated by reference. In the pump disclosed therein, a throat is formed at the bottom of the pump chamber. Upon actuation of the dispensing stem, a cylindrical member makes a positive surface to surface seal with the throat to seal off the chamber from a dip tube in communication with the container. On the return stroke of the piston, the cylinder remains empty until the member making the seal reaches almost its fully raised position whereupon communication is again established between the pump chamber and the container permitting the chamber to refill. Such pumps avoid problems which accompany ball check valves, e.g. sticking, etc.
The same manner of sealing the pump chamber is described in U.S. Pat. No. 4,274,560 in conjunction with a prepressurized pump. In the pump of the aforementioned U.S. Pat. No. 4,113,145, and in a number of the embodiments of U.S. Pat. No. 4,274,560 the throat at the inlet to the pump chamber is formed by molding the throat as part of the pump body. However, in FIG. 4 of U.S. Pat. No. 4,274,560, an alternative manner of sealing is disclosed. This alternative manner comprises forming the throat by means of a flexible insertable seal. This permits making the seal member, which is inserted into the pump chamber, of a softer plastic material than the pump body itself and softer than the cylindrical member with which it makes a seal so as to obtain a better sealing effect.
Another pump of this general type is disclosed in British Patent No. 1,486,236, in which a check valve is formed at the inlet to the pump chamber by an elastic ring closely and slidably fitted on a valve rod movable between two positions as defined by a cavity member having an annular recess larger than the outside diameter of the elastic ring.
Conventional pumps and pumps such as the type of U.S. Pat. No. 4,113,145 rely upon the operator moving the actuator and stem smoothly and firmly in order to get atomization. If the operator does not move the actuator quickly enough and smoothly enough the result is dribble.
With the recognition of the problems of pressurized atomizing dispensers releasing Freon gas into the atmospere, there was an increase in demand for a better atomizing pump dispenser which did not result in this dribble. A type of pump that accomplishes this is what is known as the prepressure pump, such as the pump of U.S. Pat. No. 4,274,560 and British Patent No. 1,486,236. A pump of this nature was first described in U.S. Pat. No. 3,399,836, which was reissued as U.S. Pat. No. Re. 28,366. Other patents of similar construction include U.S. Pat. Nos. 3,414,169, 4,144,987, 4,051,983, 4,025,046, French Pat. Nos. 2,314,772, 2,305,241, British Pat. No. 1,508,572, U.S. Pat. Nos. 4,089,442 and 4,122,982.
Such a pump is also described in U.S. Pat. No. 4,230,242. In this pump, a ball check value is formed within a valve actuator member to permit refilling of the pump immediately at the beginning of the return stroke.
U.S. Pat. No. 4,389,003, the disclosure of which is is hereby incorporated by reference, also permits immediate refilling through the use of a sliding inlet seal. That is to say, it has a flexible insertable seal such as the one in FIG. 4 of U.S. Pat. No. 4,274,560, which is slidable and which slides to open channels to permit immediate refilling of the pump.
The aforementioned prepressure pumps, as with basic atomizing pumps include a pump body in which there is formed a pump chamber, a piston disposed for reciprocal movement within the pump chamber, a dispensing stem operatively coupled to the piston and adapted to receive an atomizer head, and valve means for selectively bringing the pump chamber in to and out of communication with the container on which the pump is mounted. However, in the case of prepresure pump, the valve means comprises a valve member which in addition to sealing the inlet to the pump chamber during operation has a portion which seals the outlet from the pump chamber through the dispensing stem. The biasing means, which in conventional pumps biases the piston directly, in the prepressurized pump act against the valve member, sealing the valve member against the outlet through the dispensing stem and thereby also biasing the piston outwardly. This valve member, typically of a cylindrical shape, of course, occupies some volume of pump chamber.
In operation, when the user presses down on an actuator on the end of the pump stem, this pressure is transmitted to the piston. As a result, pressure builds up within the chamber, the pressure being equal to the available piston area times the force applied by the operator. Since the liquid within the pump chamber is not compressible, this hydraulic pressure also acts on the valve member. The inward force excerted on the valve member is equal to the pressure times its area available to the fluid. This force acts against the spring which is biasing the valve member outwardly. When the pressure in the chamber builds up to the point that the force generated overcomes the spring force, the valve member moves inwardly opening the outlet in the dispensing stem and permitting the fluid to flow out through the actuator which typically is a mechanical break-up actuator breaking up the pressurized fluid into a mist. Through this prepressure operation, it is assured that in each case there is sufficient pressure so that proper atomization takes place in the mechanical breake-up atomizer.
However, if the operator moves the actuator slowly, rather than dispensing a single puff of atomized fluid, a number of puffs, one after the other, are dispensed. This prevents reliably dispensing a one-shot measured dose. There is a desire and need for a pump which will dispense essentially all of the material in the pump chamber in a single puff. Such a pump more nearly approximates operation of metered pressurized dispensers which the public has considered preferable in many cases, but which from an environmental standpoint, are undesirable. Furthermore, in most medical applications, where a controlled dose is necessary, a single puff pump in which all of the material is dispensed in one dose is critically essential. Furthermore, there is a need for good pressure to insure that the proper atomization is maintained over the full dispensing stroke.
An additional problem which has faced manufacturers of this type of pump is that of atomizing heavier materials, such as oil, e.g., oils used for spraying in a frying pan, for example, to coat it before cooking. Because these are heavier than the typical material atomized, e.g., perfume or the like, a higher pressure is needed to break them up into small particles. However, it has been found that the typical user cannot properly operate a pump dispenser if the required operating pressure is excessive, i.e., above about five or six pounds. Thus, there is also a need for a dispenser which will dispense heavier liquids and permit their atomization without requiring a finger pressure in excess of five or six pounds.